That’s not true. The last update was 20 days ago, as can be read here: Plex for webOS (2+ UHD Televisions)
Even if you opted out of the public preview the last update was on July 30th.
Maybe you checked the date in the LG content store? You should ignore this. This is only the “launcher app” which gets updated very rarely. The “actual” app is updated without the LG content store noticing it.
Btw, another hint: Mentioning the @Plex user won’t bring any attention to this topic. This user is not active/used.
